[wdmaudiodev] SRB data block size

  • From: BlazeAudio Developer <developer@xxxxxxxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Tue, 25 Feb 2003 17:53:08 -0800


We have a stream class minidriver (on Windows XP, for a firewire audio 
device) that works fine when the internal buffering is 10ms or below, but 
we run into problems (driver starved of data) when the buffer size is 
increased. The internal buffering indirectly controls how often the driver 
completes the "pending" SRBs.

This is very similar to the problem that Windows 3.1 drivers (and Win95 as 
well as WinNT 4 drivers) experienced when the DMA buffer size was increased 
beyond a certain point. But that was directly related to how applications 
queued up the buffers.

Does anybody know what determines the amount of data that KMixer (or is it 
Sysaudio) sends to the driver before waiting for the blocks to be completed?

I tried providing the KSPROPERTY_AUDIO_LATENCY property, but nobody (KMixer 
or Sysaudio) seem to be interested in it - no get property calls come for it.

Is there a recommended maximum buffer size that KMixer assumes?



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